DOCSLIB.ORG

Natal Kicks of Stellar-Mass Black Holes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Natal Kicks of Stellar-Mass Black Holes Natal kicks of stellar-mass black holes PoS(GRB 2012)106 Melvyn B. Davies∗a, Serena Repettoab and Steinn Sigurdssonc aLund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-22100, Lund, Sweden. bDepartment of Astrophysics/IMAPP, Radbound University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands. cDepartment of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA. E-mail: [email protected], [email protected], [email protected] We investigate whether stellar-mass black holes have to receive natal kicks in order to explain the observed distribution of low-mass X-ray binaries containing black holes within our Galaxy. Such natal kicks will affect the production of compact BH-NS binaries which are possible GRB progenitors. We combine population synthesis with integrations of binary systems within the Galactic potential. We find that in a number of cases, natal kicks are in fact necessary. Further, we find that the distribution of natal kicks would seem to be similar to that of neutron stars. This result is somewhat surprising; in many pictures of stellar-mass black-hole formation, one might have expected black holes to receive kicks having the same momentum (rather than the same speed) as those given to neutron star. Gamma-Ray Bursts 2012 Conference -GRB2012, May 07-11, 2012 Munich, Germany ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Black hole kicks Melvyn B. Davies 1. Introduction Low-mass X-ray binaries containing black holes (BH-LMXBs) have been observed through- out the Galaxy. Their positions in cylindrical coordinates are shown in Figure 1. As seen in this figure, they are found at a variety of distances from the Galactic disc. These systems are thought to form from the evolution of massive stars within binaries and thus should form in the Galactic disc. Those reaching large heights from the disc must therefore have received some form of kick when the black hole was formed in a supernova explosion. This kick can have two components: one from the mass-loss associated with the supernova explosion and one due to any natal kick given to the PoS(GRB 2012)106 black hole on its formation. We have used population synthesis to produce a population of binary systems giving the bi- naries random kicks with a natal kick component drawn from various kick distributions. We then integrated the motion of the binaries within a model for the Galactic potential noting their positions at regular intervals so producing a synthetic distribution of X-ray binaries which can be compared to the observed population. Figure 1: Galactic distribution, in cylindrical coordinates, of low-mass X-ray binaries containing neutron stars or black holes: NS-LMXBs (open circles) and BH-LMXBs (filled circles). Locations and distances have been taken from [1] and [2]. Lines denote position uncertainties. 2. Results In Figure 2 we plot the positions in cylindrical coordinates of BH-LMXBs using various natal kick distributions. We find that natal kicks comparable to those inferred for neutron stars are necessary to produce a good match to the observed BH-LMXB distribution. 2 Black hole kicks Melvyn B. Davies PoS(GRB 2012)106 Figure 2: Binary population synthesis for a sample of BH-LMXBs. Natal kicks have been drawn from the Hansen & Phinney kick distribution [3] (top left) or the Arzoumanian kick distribution [4] (top right), whereas the bottom figures correspond to using natal kicks reduced by the ratio of black hole to neutron star masses as would be expected if black holes are formed via fallback of material onto neutron stars. The synthetic population is shown as small dots whereas the observed systems are shown as large dots. In Figure 3 we plot the cumulative distributions of BH-LMXBs as a function of distance from the Galactic plane. We see that the distribution of the synthetic population is a good match to the observed distribution for both the Hansen & Phinney and Arzoumanian neutron-star kick distributions [3, 4]. A very poor fit is found for the case of zero natal kick. This is also true for kick distributions reduced by the ratio of black-hole to neutron-star masses. 3. Conclusion We conclude that black holes seem likely to receive natal kicks comparable to those given to neutron stars. These results are presented in more detail in [5]. 3 Black hole kicks Melvyn B. Davies PoS(GRB 2012)106 Figure 3: Cumulative distributions of BH-LMXBs as a function of distance from the Galactic plane, for the observed systems (solid line) and for our synthetic population using different natal kicks (dotted line is for a Hansen & Phinney natal kick, dotted-dashed line is for a reduced Hansen & Phinney natal kick, short-dashed is for an Arzoumanian natal kick, short-long-dashed is for a reduced Arzoumanian natal kick, whereas long-dashed is for zero natal kick). Acknowledgments This work was supported by the Swedish Research Council (grants 2008–4089 and 2011– 3991). SR is thankful to the University of Pavia for the Erasmus grant and Andrea de Luca for helpful suggestions. MBD and SS gratefully acknowledge the hospitality of the Aspen Center for Physics. References [1] P.G. Jonker, G.Nelemans, The distances to Galactic low-mass X-ray binaries: consequences for black hole luminosities and kicks, MNRAS 354 (2004) 355 [2] F. Ozel, D. Psaltis, R. Narayan, J.E. McClintock, The Black Hole Mass Distribution in the Galaxy, ApJ 725 (2010) 1918 [3] B.M.S. Hansen, E.S.Phinney, The pulsar kick velocity distribution, MNRAS 291 (1997) 569 [4] Z. Arzoumanian, D.F. Chernoff, J.M.Cordes, The Velocity Distribution of Isolated Radio Pulsars, ApJ 568 (2002) 289 [5] M.B. Davies, S. Repetto, S. Sigurdsson, Investigating stellar-mass black hole kicks, MNRAS submitted [arXiv:1203.3077] 4.
Load more

Recommended publications
  • Arxiv:1411.0399V2 [Astro-Ph.HE] 16 Mar 2016 to the X-Ray Luminosity Indicate That PSR J1745-2900 Is Not a Rotation-Powered Pulsar but a Magnetar
    Draft version March 17, 2016 Preprint typeset using LATEX style emulateapj v. 5/2/11 THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A* Geoffrey C. Bower1, Adam Deller2, Paul Demorest3, Andreas Brunthaler4, Heino Falcke5,2,4, Monika Moscibrodzka5, Ryan M. O'Leary6, Ralph P. Eatough4, Michael Kramer4,7, K.J. Lee4, Laura Spitler4, Gregory Desvignes4, Anthony P. Rushton8,9, Sheperd Doeleman10,11, Mark J. Reid11 Draft version March 17, 2016 ABSTRACT We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic Center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 ± 11 km s−1 at position angle 22 ± 2 deg East of North at a projected separation of 0.097 pc from Sgr A*. Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A*; however, the probability of chance alignment is very small. We do show that the velocity and position is consistent with a bound orbit originating in < −1 the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of ∼ 500 km s . An origin among the isotropic stellar cluster is possible but less probable. If the pulsar remains radio-bright, multi-year astrometry of PSR J1745-2900 can detect its acceleration and determine the full three- dimensional orbit. We also demonstrate that PSR J1745-2900 exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties.
    [Show full text]
  • High Neutron Star Birth Velocities and Gravitational Radiation During Supernova Explosions
    A&A manuscript no. (will be inserted by hand later) ASTRONOMY AND Your thesaurus codes are: ASTROPHYSICS 01 (02.07.2; 08.14.1; 08.19.4) 19.5.2018 High Neutron Star Birth Velocities and Gravitational Radiation during Supernova Explosions S.N.Nazin1 and K.A. Postnov1,2 1 Sternberg Astronomical Institute, Moscow University, 119899 Moscow, Russia 2 Faculty of Physics, Moscow University, 117234 Moscow, Russia Received ... 1996, accepted ..., 1996 Abstract. Assuming the observed pulsar velocities to precessing binary pulsar orbit in PSR J0045-7319 in the originate during asymmetric collapse of stellar cores, we SMC (Kaspi et al. 1996). The collapse asymmetry result- compute the amplitude of gravitational waves emitted ing in the kick velocity of a neutron star at birth may during type II and Ib supernova explosions and their de- be due to different reasons. For example, recent calcula- tection rate from within a distance of 30 Mpc. At the tions of Burrows & Hayes (1996) has shown the ability rms-level of advanced laser interferometers h 10−22 at of neutrino anisotropic emission to produce kick velocities frequencies 300 1000 Hz the expected rate is about≈ 1 per of 400-500 km/s, as observed (see also Imshennik 1992; year. − Bisnovatyi-Kogan 1993). One of the consequences of Lyne and Lorimer’s result Key words: Gravitational waves — Stars: neutron — was a recognition that the kick velocity imparted to a neu- Supernovae: general tron star at birth has a power-law asymptotic form at high velocities (Lipunov, Postnov & Prokhorov 1996a,b). Using direct Monte-Carlo calculations of binary star evolution (the so-called “Scenario Machine”), they found that the Supernova explosions are among the most violent Lyne-Lorimer pulsar transverse velocities are best repro- events known in nature.
    [Show full text]
  • Pulsar Kicks and Γ-Ray Burst
    A&A 472, 1–3 (2007) Astronomy DOI: 10.1051/0004-6361:20077200 & c ESO 2007 Astrophysics Pulsar kicks and γ-ray burst X. H. Cui1,H.G.Wang2,R.X.Xu1, and G. J. Qiao1 1 Astronomy Department, School of Physics, Peking University, Beijing 100871, PR China e-mail: [xhcui,rxxu,gjq]@bac.pku.edu.cn 2 Center for Astrophysics, Guangzhou University, Guangzhou 510400, PR China e-mail: [email protected] Received 31 January 2007 / Accepted 5 June 2007 ABSTRACT Aims. We use the supernova-GRB (γ-ray burst) association and assume that the GRB asymmetric explosions produce pulsars in order to test the consistency of distributions of modeled and observed pulsar-kick velocities. Methods. The deduced distribution of kick velocity from the model of GRB and the observed kick distribution of radio pulsars are checked by a K-S test. Results. These two distributions are found to come from the same parent population. Conclusions. This result may indicate that GRBs could really be related to supernova and that the asymmetry of GRB associated with supernova would cause the pulsar kick. Key words. stars: pulsars: general – gamma rays: bursts – stars: neutron – dense matter 1. Introduction naturally result in kicks on quark stars. But how can we test this idea? These issues are focus here. The difficulty of reproducing two kinds of astronomical bursts are challenging today’s astrophysicists to find realistic explo- Quark stars could reproduce the observational features of sive mechanisms. On one hand, γ-ray bursts (GRBs) are puz- pulsar-like stars well (Xu 2006). Radio pulsars have long been zling phenomena, the center engine of which is still an outstand- recognized of having high space velocities (e.g.
    [Show full text]
  • Pulsar Kicks from Neutrino Oscillations
    CORE Metadata, citation and similar papers at core.ac.uk Provided by CERN Document Server UCLA/98/TEP/30 Pulsar kicks from neutrino oscillations Alexander Kusenko Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 Gino Segr`e Department of Physics, University of Pennsylvania, Philadelphia, PA 19104 (November, 1998) Neutrino oscillations can explain the observed motion of pulsars. We show that two different models of neutrino emission from a cooling neutron star are in good quantitative agreement and predict the same order of magnitude for the pulsar kick velocity, consistent with the data. PACS numbers: 97.60.Gb, 14.60.Pq I. INTRODUCTION trino oscillations1. The result obtained in Ref. [6] was in- + correct because the neutrino absorption νen e−p was neglected and also because the different neutrino→ opaci- ties were assumed to be equal to each other. We empha- We recently suggested [1,2] that the observed proper size that in the absence of charged-current interactions motions of pulsars [3] may be the result of neutrino os- the kick from the active neutrino oscillations [1] should cillations in the hot neutron star born in a supernova ex- vanish. plosion. Neutrinos are the only significant cooling agents We will show that, after the charged-current interac- during the first 10 seconds after the onset of the super- tions are included, the two models are, in fact, in good nova, and they carry away most of the energy liberated agreement, as they should be. in the gravitational collapse, 1053erg. A 1% asymme- try in the distribution of neutrinos∼ can account for the measured pulsar velocities 500 km/s.
    [Show full text]
  • Neutron-Star Birth Kicks
    Binary Radio Pulsars ASP Conference Series, Vol. 328, 2005 F. A. Rasio and I. H. Stairs Neutron-Star Birth Kicks Philipp Podsiadlowski Department of Astrophysics, University of Oxford, Oxford, OX1 3RH, UK, [email protected] Eric Pfahl Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA, [email protected] Saul Rappaport Department of Physics and Center for Space Research, Massachusetts Institute of Technology, [email protected] Abstract. We summarize the evidence for large natal supernova kicks from the observed distribution of pulsar velocities and discuss the di±culties in mod- elling the intrinsic natal kick distribution. We review the status of the neutron- star retention problem in globular clusters and some of the suggested solutions. We then present evidence from the orbital characteristics of a recently identi¯ed separate class of Be X-ray binaries that require neutron stars with very low birth kicks and propose a dichotomous scenario for neutron-star kicks, where neutron stars born in originally relatively close binaries receive small kicks and provide a theoretical framework for such a scenario. Finally, we summarize the main pulsar kick mechanisms that have been proposed and show the results of some of the most recent hydrodynamical core-collapse simulations. 1. Introduction It is now almost universally accepted that neutron stars receive a substantial kick when they are born, presumably due to an asymmetry in the core collapse or the subsequent supernova explosion, but neither the exact distribution of kick velocities nor the physical origin of these kicks are properly understood. In this contribution, we ¯rst summarize the arguments supporting substantial natal kicks and the constraints on the kick-velocity distribution, but then present the case for the need of low-velocity kicks for at least a subset of neutron stars and propose a dichotomous kick scenario.
    [Show full text]
  • Arxiv:2101.06145V2 [Astro-Ph.HE] 23 Jun 2021
    Draft version June 24, 2021 Typeset using LATEX twocolumn style in AASTeX631 Analyzing the Galactic pulsar distribution with machine learning M. Ronchi ,1, 2 V. Graber ,1, 2 A. Garcia-Garcia ,1, 2, 3 N. Rea ,1, 2 and J. A. Pons 3 1Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, 08193, Barcelona, Spain 2Institut d'Estudis Espacials de Catalunya (IEEC), Carrer Gran Capit`a2{4, 08034 Barcelona, Spain 3Departament de F´ısica Aplicada, Universitat d'Alacant, 03690 Alicante, Spain (Accepted ApJ) ABSTRACT We explore the possibility of inferring the properties of the Galactic neutron star population through machine learning. In particular, in this paper we focus on their dynamical characteristics and show that an artificial neural network is able to estimate with high accuracy the parameters which control the current positions of a mock population of pulsars. For this purpose, we implement a simplified population-synthesis framework (where selection biases are neglected at this stage) and concentrate on the natal kick-velocity distribution and the distribution of birth distances from the Galactic plane. By varying these and evolving the pulsar trajectories in time, we generate a series of simulations that are used to train and validate a suitably structured convolutional neural network. We demonstrate that our network is able to recover the parameters governing the kick-velocity and Galactic height distribution with a mean relative error of about 10−2. We discuss the limitations of our idealized approach and study a toy problem to introduce selection effects in a phenomenological way by incorporating the observed proper motions of 216 isolated pulsars.
    [Show full text]
  • Full White Paper
    LIGO SCIENTIFIC COLLABORATION VIRGO COLLABORATION Document Type LIGO–T1400054 VIR-0176A-14 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics (2014-2015 edition) The LSC-Virgo Search Groups, the Data Analysis Software Working Group, the Detector Characterization Working Group and the Computing Committee WWW: http://www.ligo.org/ and http://www.virgo.infn.it Processed with LATEX on 2014/11/21 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics Contents 1 The LSC-Virgo White Paper on Data Analysis 4 1.1 Searches for Signals from Compact Binary Coalescences . .5 1.2 Searches for Generic Transients, or Bursts . .7 1.3 Searches for Continuous Wave Signals . .9 1.4 Searches for Stochastic Gravitational Wave Backgrounds . 11 1.5 Characterization of the Detectors and their Data . 13 1.6 Data Calibration . 15 1.7 Hardware Injections . 16 1.8 Computing and Software . 17 2 Previous Accomplishments (2013-2014) 19 2.1 Burst Working Group . 19 2.2 Compact Binary Coalescences Working Group . 19 2.3 Continuous Waves Group . 20 2.4 Stochastic Group . 21 2.5 Detector Characterization . 21 3 Search Plans for the Advanced Detector Era 23 3.1 All-Sky Burst Search . 24 3.2 Search For Binary Neutron Star Coalescences . 29 3.3 Search for Stellar-Mass Binary Black Hole Coalescences . 37 3.4 Search For Neutron Star – Black Hole Coalescences . 45 3.5 Search for GRB Sources of Transient Gravitational Waves . 57 3.6 Search for Intermediate Mass Black Hole Binary Coalescences . 64 3.7 All-sky Searches for Isolated Spinning Neutron Stars .
    [Show full text]
  • Asymmetric Neutrino Reaction and Pulsar Kick in Magnetized
    AsymmetricAsymmetric Neutrino Neutrino Reaction Reaction and and Pulsar Pulsar Kick Kick inin Magnetized Magnetized Proto Proto--NeutronNeutron Stars Stars inin Fully Fully Relativistic Relativistic Framework Framework TomoyukiTomoyuki MaruyamaMaruyama BRS,BRS, Nihon Nihon Univ. Univ. (Japan) (Japan) ToshitakaToshitaka KajinoKajino NaoNao,, Univ. Univ. of of Tokyo Tokyo (Japan)(Japan) NobutoshiNobutoshi YasutakeYasutake Univ.Univ. of of Tokyo Tokyo (Japan) (Japan) MyungMyung--kiki CheounCheoun SoongsSoongs Univ.Univ. (Korea)(Korea) ChungChung--YeolYeol RyuRyu SoongsSoongs Univ.Univ. (Korea) (Korea) ++ JunJun Hidaka Hidaka NaoNao (Japan)(Japan) G.J.G.J. Mathews Mathews Univ.Univ. of of Notre Notre Dome Dome (USA) (USA) TM et al., Phys. ReV. D83, 081303(R) (2011) 1 §§1.1. IntroductionIntroduction 2 High Density Matter Study ⇒ Exotic Phases : Strange Matter, Ferromagnetism Meson Condensation, Quark matter They may exist inside Neutron Stars Observable Information ‥‥Neutrino Emissions S.Reddy, M.Prakash and J.M. Lattimer, P.R.D58 #013009 (1998) Influence from Hyperons Λ，∑ Magnetar 1015G in surface 1017-19G inside (?) Magnetic Field → Large Asymmetry ？ P. Arras and D. Lai, P.R.D60, #043001 (1999) Neutrino Scattering & Absorption S. Ando, P.R.D68 #063002 (2003) in Surface Region Non-Relativistic Our Works ⇒ Neutrino Reactions on High Density Matter wih Strong Mag. Fields PulsarPulsar Kick Kick CasA A.G.Lyne, D.R.Lomier, Nature 369, 127 (94) Asymmetry of Supernova Explosion kick and translate Pulsar with Kick Velocity: Average … 400km/s， Highest … 1500km/s Explosion Energy ~ 1053 erg http://chandra.harvard.edu/photo/ (almost Neutrino Emissions) 2004/casa/casa_xray.jpg 1% Asymmetry are sufficient to explain the Pulsar Kick D.Lai & Y.Z.Qian, Astrophys.J.
    [Show full text]
  • The Evolution of Hierarchical Triple Star-Systems
    Toonen et al. Computational Astrophysics and Cosmology (2016)3:6 DOI 10.1186/s40668-016-0019-0 METHODOLOGY OpenAccess The evolution of hierarchical triple star-systems Silvia Toonen* , Adrian Hamers and Simon Portegies Zwart Abstract Field stars are frequently formed in pairs, and many of these binaries are part of triples or even higher-order systems. Even though, the principles of single stellar evolution and binary evolution, have been accepted for a long time, the long-term evolution of stellar triples is poorly understood. The presence of a third star in an orbit around a binary system can significantly alter the evolution of those stars and the binary system. The rich dynamical behaviour in three-body systems can give rise to Lidov-Kozai cycles, in which the eccentricity of the inner orbit and the inclination between the inner and outer orbit vary periodically. In turn, this can lead to an enhancement of tidal effects (tidal friction), gravitational-wave emission and stellar interactions such as mass transfer and collisions. The lack of a self-consistent treatment of triple evolution, including both three-body dynamics as well as stellar evolution, hinders the systematic study and general understanding of the long-term evolution of triple systems. In this paper, we aim to address some of these hiatus, by discussing the dominant physical processes of hierarchical triple evolution, and presenting heuristic recipes for these processes. To improve our understanding on hierarchical stellar triples, these descriptions are implemented in a public source code TrES, which combines three-body dynamics (based on the secular approach) with stellar evolution and their mutual influences.
    [Show full text]
  • How Fast Could a Proto-Pulsar Rotate?
    Chin. J. Astron. Astrophys. Vol. 2 (2002), No. 6, 533–538 Chinese Journal of ( http://www.chjaa.org or http://chjaa.bao.ac.cn ) Astronomy and Astrophysics How Fast Could a Proto-pulsar Rotate? Ren-Xin Xu ?, Hong-Guang Wang and Guo-Jun Qiao Department of Astronomy, School of Physics, Peking University, Beijing 100871 Received 2002 June 10; accepted 2002 September 2 Abstract According to two estimated relations between the initial period and the dynamo-generated magnetic dipole field of pulsars, we calculate the statistical distributions of pulsar initial periods. It is found that proto-pulsars are very likely to have rotation periods between 20 ms and 30 ms, and that most of the pulsars rotate initially at a period < 60 ms. Our result supports the asymmetric neutrino emission model for pulsar kick. Key words: pulsars — neutron stars — magnetic fields 1 INTRODUCTION Pulsars increase our knowledge of nature by providing us with an unusual physical condition (e.g., Wu et al. 2002; Xu et al. 2001). However, one of the essential parameters, the initial 1 period P0 of proto- pulsar, which may reveal precious information of dynamical supernova process, is poorly known. Actually there are three approaches to estimate P0 in the literature. n−1 1) The period P0 can be found via T = P/[(n − 1)P˙ ][1 − (P0/P ) ] if the age T and the braking index n ≡ ΩΩ¨/Ω˙ 2 (Ω = 2π/P the angular velocity of rotation) are measured (e.g., Kaspi et al. 1994; Migliazzo et al. 2002), where P is the observed rotation period.
    [Show full text]
  • Sustained Petascale in Action: Enabling Transformative Research 2019 Annual Report Sustained Petascale in Action: Enabling Transformative Research 2019 Annual Report
    SUSTAINED PETASCALE IN ACTION: ENABLING TRANSFORMATIVE RESEARCH 2019 ANNUAL REPORT SUSTAINED PETASCALE IN ACTION: ENABLING TRANSFORMATIVE RESEARCH 2019 ANNUAL REPORT Editor Catherine Watkins Creative Director Steve Duensing Graphic Designer Megan Janeski Project Director William Kramer The research highlighted in this book is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana–Champaign and its National Center for Supercomputing Applications. Visit https://bluewaters.ncsa.illinois.edu/science-teams for the latest on Blue Waters- enabled science and to watch the 2019 Blue Waters Symposium presentations. CLASSIFICATION KEY To provide an overview of how science teams are using Blue Waters, researchers were asked if their work fit any of the following classifications (number responding in parentheses): Data-intensive: Uses large numbers of files, large disk space/ DI bandwidth, or automated workflows/offsite transfers, etc. (83) GPU-accelerated: Written to run faster on XK nodes than on GA XE nodes (55) LEADING BY EXAMPLE Thousand-node: Scales to at least 1,000 nodes for production TN science (74) Memory-intensive: Uses at least 50 percent of available memory MI on 1,000-node run (21) BW Only on Blue Waters: Research only possible on Blue Waters (43) The National Center for Super- Earlier in 2020 I was privileged to be part of a del- computing Applications (NCSA) egation of University of Illinois leaders that partici- Multiphysics/multiscale: Job spans multiple length/time scales or was funded in 1986 to enable dis- pated in discussions on the next frontier of AI, data MP physical/chemical processes (59) coveries not possible anywhere science, and design thinking with Illinois alumnus TABLE OF else.
    [Show full text]
  • Pulsar Kicks by Anisotropic Neutrino Emission from Quark Matter in Strong Magnetic fields
    A&A 489, 281–289 (2008) Astronomy DOI: 10.1051/0004-6361:20078530 & c ESO 2008 Astrophysics Pulsar kicks by anisotropic neutrino emission from quark matter in strong magnetic fields I. Sagert and J. Schaffner-Bielich Institute for Theoretical Physics/Astrophysics, Goethe University, Max-von-Laue-Straße 1, 60438 Frankfurt, Germany e-mail: [email protected] Received 22 August 2007 / Accepted 24 May 2008 ABSTRACT Aims. We critically discuss a pulsar acceleration mechanism based on asymmetric neutrino emission from the direct quark Urca process in the interior of proto neutron stars. Methods. The neutrinos are emitted by the cooling strange quark matter core with an anisotropy caused by a strong magnetic field. We calculate the kick velocity of the proto neutron star in dependence of the temperature and radius of the quark phase. The results are compared with the necessary magnetic field strength, as well as the neutrino mean free path. Results. We find that within a quark phase radius of 10 km and temperatures higher than 5 MeV kick velocities of 1000 km s−1 can be reached only when neutrino quark scattering is ignored. When taking the neutrino mean free paths in quark matter into account kick velocities higher than 100 km s−1 cannot be reached. The same holds even when effects from colour superconductivity are included. For pulsar kicks powered by quark phase transitions from an ungapped quark phase to the CFL phase the final velocity depends crucially on the pairing gap and the quark chemical potential and reaches 1000 km s−1 only in marginal cases.
    [Show full text]